Jessica, this is why you never copy from someone else! Often these people just seem to want to brag about how many people are in their tree. One person posts unverified data in their tree and 100 others copy these mistakes into their trees and the mistake snowballs. Don't be one of those people.
Don't concern yourself about what someone else has in their tree, just worry about your own. If worried then make your tree private. Do your own research and prove the source of each of your entries.
Pieter Hoekstra <sold@...>
Moss / Moses, De Costa - London and Brighton
Barnett, Da Costa, Lazarus, Joseph, Judah, Solomon - London